28 nm Integrated Circuit for PIXel detector

IC-PIX28 (Integrated Circuit for PIXel detectors) is an analog read-out front-end fabricated in 28 nm Bulk-CMOS technology to process the charge signal produced by the pixel detector having 100 fF parasitic capacitance. The device is composed by a Charge Sensitive Pre-amplifier (CSPreamp) and a comparator. The development of IC-PIX28 manages several issues due to the poor analog performance of the standard-process MOS transistors in 28 nm Bulk-CMOS technology, whose choice is motivated by the expected rad-hard performance up to 1 Grad of Total Ionizing Dose. IC-PIX28 achieves performance robustness and low-power consumption by specific circuital solutions and it operates from a single 900 mV supply voltage. The full IC-PIX28 read-out channel consumes 4.3 $\mu$W. The CSPreamp performs 35 mV/fC sensitivity, 40 dB Signal-to-Noise Ratio, and 0.033 fC (204 e${}_{\mathrm{rms}}^{-}$) Equivalent Noise Charge. Moreover, a switched-capacitors inverter-based comparator performs the Time-over-Threshold (ToT, at very low power consumption) with a measured ToT range of 500 ns convertible in a digital word with a high bit resolution (> 14).